You will have to play any costs associated with playing that card. It's treated as thought you were normally playing that card (i.e. from your hand), you go through the same process of paying mana and additional costs for it like you would for other spells. So if you search one of your opponent's lands and play it, you wouldn't be able to play a land from your hand that turn. If you yoinked a spell, you have to pay any of the normal costs you would normally pay for playing that spell.
Rhadamanthus says... Accepted answer #1
Yes, because card:Praetor's Grasp doesn't give you any special permissions to not pay the mana cost (compare it to a card like Knowledge Exploitation ), that means you have to pay it when you play the card.
May 13, 2011 8:57 a.m.